The subject of the present invention is a breakable electric contact device which can be fitted in particular into a junction block.
Certain electric contacts may be installed in environments where there is contamination of various kinds. This may be metallurgical contamination resulting in oxidation of the contacts as a result of a corrosive environment, or contamination with dust. What this means is that when the contacts are contaminated, there is a lack of reliability of the electrical connection when the electric contact is closed. The contacts involved may consist, for example, of conducting strips in the form of stirrups, associated with a conducting piece in the shape of a moving blade intended to become introduced, by pivoting, between the two stirrups in order to close the contact.
The object of the invention is to provide a breakable electric contact device, in which the reliability of the electric contact is ensured, without the need for special maintenance, even if the installation is in a contaminating environment.
To this end, the device to which it relates, of the type comprising two conducting strips between which an electric contact can be made using a conducting piece in the form of a moving blade, at least one of the faces of which is intended to come into contact with the conducting strips, is characterized in that it comprises two cleaning strips which, located in front of the conducting strips in the direction of travel of the moving blade toward the contact-closed position, are intended to scrape at least the region of each face or the moving blade that is intended to press against a conducting strip.
Thus, the conducting piece coming into contact with the cleaning strips before closing the electric contact is rid of all traces of oxidation or dust in its regions of contact with the conducting strips.
Advantageously and so as to allow adequate pressure to be exerted in order to scrape the conducting piece, each cleaning strip is made of a rigid and elastic material.
When the conducting strips are in the shape of stirrups, each cleaning strip associated with a stirrup has a slot delimited by two sharp edges intended to scrape the two faces of the moving blade.
According to one embodiment, when the moving blade is mounted so that it pivots about an axis transversal to the openings of the stirrups and offset laterally with respect to the two stirrups, the two cleaning strips associated with the two stirrups are parallel to these stirrups and arranged on the side of each stirrup furthest from the axis of pivoting of the moving blade.
As the cleaning strips play no part in the electrical connection, it is of little importance whether or not the material of which they are made is conducting.
According to a first option, each cleaning strip is independent of the corresponding stirrup and pressed against the latter.
According to another option, each cleaning strip consists of the actual constituent part of the stirrup which is bent back on itself.
In order to clean adequately the regions of the moving blade which are to come into contact with the contact strips, each cleaning strip protrudes from the corresponding stirrup on the entry side thereof, the cleaning strip furthest from the axis of rotation of the moving blade protruding more than the cleaning strip closest to this axis. The offset of each strip with respect to the corresponding stirrup depends on the radius of pivoting of the moving blade.
According to another embodiment of this device, when the moving blade is mounted so that it can be moved in terms of translation between the position in which the electric contact is open and the position in which it is closed, each cleaning strip is situated forward in the direction of travel of the moving blade and aligned, in the direction of travel of the moving blade, with the region of contact between the moving blade and a conducting strip.